Hydraulic cushion cylinder head arrangement



5 Sheets-Sheet 1 W. H. PETERSON HYDRAULIC CUSHION CYLINDER HEAD ARRANGEMENT R, 2. F k

Dec. 14, 1965 Filed Jan. 13, 1964 Dec. 14, 1965 w. H. PETERSON 3,223,401

HYDRAULIC CUSHION CYLINDER HEAD ARRANGEMENT Filed Jan. 13, 1964 5 Sheets-Sheet 2 INVENTOR. wlLUAM H.PETERSON BY I -Q2 Dec. 14, 1965 w. H. PETERSON 3,223,401

HYDRAULIC CUSHION CYLINDER HEAD ARRANGEMENT Filed Jan. 13, 1964 5 Sheets-Sheet 5 INVENTOR. WlLUAM H. PETERSON Dec. 14, 1965 w. H. PETERSON 3,223,401

HYDRAULIC CUSHION CYLINDER HEAD ARRANGEMENT Filed Jan. 13, 1964 5 Sheets-Sheet 5 T QT .11

INVENTOR. W\LL\AM HPETER$0N United States Patent 3,223,401 HYDRAULIC CUSIHON CYLINDER HEAD ARRANGEMENT William H. Peterson, Homewood, IIL, assignor to Pullman Incorporated, Chicago, Ill., a corporation of Delaware Filed Jan. 13, 1964, Ser. No. 337,193 8 illaims. (Cl. 267-1) The present invention relates to hydraulic cushion devices and more particularly to an improved arrangement for preventing fluid leakage in a hydraulic cushion device of the type comprising essentially two relatively reciprocating components having hydraulic fluid arranged therebetween so as to be operative upon the application of an impact force on one of the components to dissipate a portion of the kinetic energy of the impact.

The cushion device to which the improvement of the present invention relates includes generally a cylinder having a closed end and an open end. Reciprocable within the cylinder is a fluid displacement means including a piston head fixed to one end of a piston rod which extends outwardly of the open end thereof. Disposed inwardly of the open end of the cylinder is an intermediate cylinder head to which there is fixed one end of a flexible boot reservoir of which the other end is fixed to the piston rod extending through the intermediate cylinder head. The intermediate cylinder head is constructed such that there is fluid communication between the boot reservoir and the cylinder whereby the boot reservoir closes oil the open end of the cylinder and receives hydraulic fluid displaced from the cylinder upon the application of an impact force causing relative movement between the piston head and the cylinder.

Heretofore, difliculties have been encountered in providing an adequate seal at the contacting surfaces of the intermediate cylinder head and the inner wall of the cylinder bore such that hydraulic fluid leaked therethrough. Such leakage of the hydraulic fluid from the cylinder is undesirable in that it reduces the cushion efliciency of the device.

It is accordingly an object of the present invention to provide a new and improved means for fastening the intermediate cylinder head within the cylinder in a manner which obviates the hydraulic fluid leakages as occurred heretofore.

It is a further object to provide a new and improved means for fastening the intermediate cylinder head within the cylinder which is of simple construction and economical to manufacture.

The present invention also relates to the hydraulic fluid i charging structure which is employed to introduce the hydraulic fluid into the cylinder and when the cylinder is fully charged to close off the passageway through which the hydraulic fluid is introduced. Heretofore, the fluid charging structure has been in the form of a check valve assembly located on the hydraulic cushion device so as to be subjected to the high fluid pressure forces present therein during relative reciprocating movement of the components upon impact. When thus located on the high fluid pressure side difficulty is encountered in preventing hydraulic fluid leakage past the check valve assembly.

It is accordingly a further object of the invention to provide the cushion device with a new and novel charging check valve structure for charging the cushion device with hydraulic fluid which is constructed and located so as to obviate the fluid leakage problems as occurred heretofore.

Further objects and features will hereinafter appear.

In the drawings:

FIG. 1 is a fragmentary cross-sectional view of a hydraulic cushion device embodying the present invention with the components being shown in the normal extended or neutral position thereof;

FIG. 2 is a fragmentary cross-sectional view of the hydraulic cushion device, but showing the components in the contracted position;

FIG. 3 is a greatly enlarged fragmentary cross-sectional view of the left end portion of the hydraulic cushion device as viewed in FIG. 2;

FIG. 4 is an enlarged cross-sectional view taken generally along the lines 44 of FIG. 3;

FIG. 5 is an enlarged fragementary cross-sectional view taken generally within the encircled portion of FIG. 3;

FIG. 6 is an enlarged fragmentary view similar to FIG. 5, but showing the relative positions of the seal forming members employed to form a fluid-tight seal at the contacting surfaces of the intermediate cylinder head and the inner wall of the bore prior to forming the fluid-tight seal;

FIG. 7 is a perspective view of the bendable clip of the seal forming members;

FIG. 8 is an enlarged cross-sectional view taken generally along the lines 88 of FIG. 3 and showing in particular the details of the hydraulic fluid charging check valve and the structure for fastening the cylinder head on the end of the piston rod;

FIG. 9 is a cross-sectional view taken generally along the lines 9-9 of FIG. 8;

FIG. 10 is a fragmentary cross-sectional view showing an embodiment for fastening the intermediate cylinder head in a manner forming a fluid-tight seal along the contacting surface; and

FIG. 11 is a fragmentary cross-sectional view similar to FIG. 10 but showing the position of the components of the fastening arrangement prior to forming the fluidtight seal.

Referring now in particular to FIGS. 1 and 2, there is shown a cushion device 10 embodying the present invention including generally a cylinder 11 having a bore 12 charged with a suitable hydraulic fluid; a fluid displacement means or piston rod-piston assembly 13 reciprocable within the cylinder bore 12 between the normal fully extended position (FIG. 1) and to a contracted position (FIG. 2) upon the application of an impact force to the device, and being operative to displace fluid within the bore 12 to dissipate a portion of the kinetic energy of the impact force; a metering pin 14 for controlling the rate of displacement of the fluid within the bore 12 to provide an approximate constant force travel closure characteristic to the device; and a resilient or return spring means 16 disposed between the fluid displacement means 13 and the cylinder 11 for returning the members to their fully extended position upon dissipation of the shock impact force.

The cylinder 11 includes a tubular shell 17 formed preferably from a rigid metallic preformed tube capable of withstanding the internal pressures to which the cylinder is subject during use. The shell 17 may be formed of cold drawn steel tubing of which the inner wall is formed with a smooth finish to permit eflicient operation of the fluid displacement means therein.

The shell 17 is closed at one end by a cylinder head 18 having a groove 19 formed therein for receiving the end of the shell 17 and the latter is fixed therein as by welding to form a leak-proof joint. The cylinder head 18 which may be formed of any convenient contour, for example, circular, rectilinear or the like, is sized to project outwardly of the outer diameter of the shell 17 to form a retaining ledge against which one end of the resilient return spring means 16 abuts.

As shown, the other end of the shell 17 may be formed with a boot chamber bore 21 of larger diameter than the cylinder bore 12. Disposed within the boot chamber bore 21 is an intermediate cylinder head 22 having an axial opening 23. The intermediate cylinder head 22 may be formed at the inner end, which abuts a shoulder 24 with an inner section 26 having an outer diameter substantially equal to the diameter of the boot chamber bore 21, an intermediate section 27 of somewhat lesser outer diameter than the inner section 26, and a boss 28 on which one end of a flexible boot reservoir 29 is secured as more fully to be explained hereinafter.

Fixing the intermediate cylinder head within the boot chamber bore 22 is a snap ring 31 disposed within a groove 32 formed in the inner wall. The snap ring 31 is engageable with a collar 33 threadably fastened on the outer end of the intermediate section 27 of the intermediate cylinder head such that the inner section 26 of the latter is held firmly engaged with the shoulder 24.

The collar 33 forms part of the structure of the present invention for forming an effective fluid-tight seal about the periphery of the intermediate cylinder head 22 with the inner wall of the boot chamber bore 21. To this end the seal forming structure further includes a compressible sealing gasket 34 such as an O-ring which slidably encircles the intermediate section 27 adjacent the outer shoulder 36 on the inner section 28. Also slidably disposed on the intermediate section 27 between the collar 33 and the sealing gasket 34 is a metal ring 37. Disposed between the collar 33 and the metal ring 37 are a plurality of clip members 38.

As shown in FIG. 7 the clip members 38 are of substantially rectangular contour and are formed intermediate the lengths thereof with a necked portion 39 to facilitate the bending thereof. The O-ring 34, the metal ring 37, the collar 33 and the metal clip members 38 bent as shown are assembled on the intermediate cylinder head 22 as shown in FIG. 6 prior to the installation of the latter within the boot chamber bore 21. The bent metal clip members 38 are radially spaced about the periphery of the intermediate section 27 with the opposite ends thereof disposed within respective peripheral grooves 41 and 42 formed along the lower inner edges of the collar 33 and metal or compression ring 37. The bent metal clip members 38 are angularly spaced complementary to angularly spaced access openings 43 provided in the tubular shell 17 so as to be aligned therewith when the intermediate cylinder head is fastened within the bore by means of the snap ring 31.

An appropriate tool such as a punch or the like is inserted through the access openings 43 to straighten the clips 38 as shown in FIG. 5. Upon straightening of the clips 38, the compression ring 37 is slidably urged to the right as viewed in FIGS. and 6 so that the O-ring 34 is compressed between the latter and the shoulder 36. In this manner the O-ring 34 is tightly engaged with the outer periphery of the intermediate section 27 and the inner wall of the boot chamber 21 so as to form a fluidtight seal.

Referring now to FIGS. and 11, there is shown a second embodiment for securing the intermediate cylin der within a cylinder wherein the bore 112 is of substantially constant diameter along its length. As shown, cylinder 111 includes a cylindrical shell or tube, an intermediate cylinder head 122 having an axial opening through which the piston rod of the fluid displacement means 13 extends to form an annular opening providing communication between the hydraulic fluid-filled bore 112 and the flexible boot reservoir disposed in the boot chamber adjacent the open end of the cylinder.

The intermediate cylinder head 122 may be formed of steel and includes an inner section 123 having a lesser diameter than the bore 112, an outer section 124 having a diameter substantially equal to the bore 112, and a boss 126 to which one end of the flexible boot reservoir or invaginating tube 29 is fixed. To provide a shoulder 127 opposing in spaced relationship the shoulder 128 on the outer section 124, there may be fixed as by Welding across the inner face of inner section 123 an annular plate 129.

Disposed about the inner section 123 adjacent the shoulder 127 is a compressible sealing gasket or quadrant ring 131, and between the quadrant ring 131 and the shoulder 128 is a metal compression ring 132. The compression ring 132 is formed along one of its upper edges with an inclined camming surface which is contacted by the conical head 133 of radially spaced fastening screws 134 threaded into the cylinder head shell 117.

As shown, the fastening screws 134 are a commercially available type, preferably of the self-locking type including a resilient plastic insert 136. The conical end 133 of each of the screws 134 upon being threaded into the shell 117 engages the inclined camming surface 130 so that upon further turning toward the seated position thereof as the unthreaded shank portion 137 bears against the shoulder 128, the compression ring 132 is moved to the right as viewed in FIGS. 10 and 11. Movement of the compression ring to the right causes the resilient quadrant ring 131 to be compressed between the outer periphery 141 of the compression ring 132 and the shoulder 127. Upon further turning to the seated position shown in FIG. 10 the conical end 133 of each of the fastening members 134 is received within a complementary formed recess 138 and the unthreaded shank portion 137 bears along one side thereof against the shoulder 128 and along the other side against vertical inner face 139 of the compression ring 132. In this manner the fastening members 134 serve to fix the cylinder head within the cylinder bore 112 and at the same time maintain the quadrant ring 131 compressed to form a fluid-tight seal between the inner wall of the cylinder bore and the outer periphery of the intermediate cylinder head 123.

The fluid displacement means 13 includes a piston rod 44 to one end of which there is fixed a piston head 46, which is reciprocable within the bore 12 between the cylinder head 18 and the intermediate cylinder head 22. Fastened to the other end of the piston rod 44 is a second cylinder or buffer head 47.

The piston rod 44 is of hollow construction including a bore 48 and may be formed of a rigid material such as cold drawn steel. Radially spaced ports 49 are formed in the piston rod 44 adjacent to the piston head 46 for providing communication between the piston rod bore 48 and the cylinder bore 12.

The piston head 46 is preferably formed from a metal such as steel and comprises a disk-like body having a planar forward face 51 and a planar rearward face 52. The planar rearward face 52 merges it into a conical feed surface 53 which terminates in a rim 54 which defines the perimeter of an orifice 56 formed coaxially in the piston head 46. The piston head 44 is formed on its forward face 51 with a recess 57 which receives the terminal end of the tubular piston rod 44 and the latter is fixed thereto as by welding.

For guiding the fluid displacement means for relative telescoping movement within the cylinder bore 12 and for forming a seal between the inner wall of the cylinder and the piston head 46, the latter is provided with an elevated seal forming and guiding surface 58. In this connection it is to be mentioned that the cushion device 10 is primarily intended for use in railway vehicle car structures for providing lading and car body protection. When thus employed, the cushion device 10 is disposed between the coupler carrying structure and the lading supporting structure so as to absorb a suflicient portion of the energy of impact to protect the lading and car body from damage. The structural environment in which the devices are em ployed is such that relative cocking may occur. This condition may result in galling between the metallic surfaces of the piston head and the cylinder wall.

To preclude such galling and at the same time to form a sealing surface the seal forming and guiding surface 58 may be a split ring formed preferably from a laminated phenolic resin. The split ring 58 is seated within a peripheral groove 59 formed in the piston head 46 such that the outer circumference of the ring 58 contacts the inner wall of the bore above the periphery of the metallic piston head 46. The guiding and sealing ring 58 which is primarily characterized by its non-affinity for the metallic surface and its ability to conform to the contour of the inner wall forms an cflicient and effective sealing and guiding means.

The tubular piston rod 44 is of lesser diameter than the diameter of the axial opening 23 in the intermediate cylinder head 22 so as to define an annular opening 61 which provides communication between the bore 12 and the flexible boot reservoir 29. The flexible boot reservoir or invaginating tube 29 is formed of a fluid-impervious flexible material which is capable of resisting the corrosive or deteriorating effects which may be present in the hydraulic fluid employed in the device and advantageously may be a neoprene-buna type of rubber having special additives for low temperatures flexibility. The invaginating tube 29 is fixed at one end to the boss 28 of the intermediate cylinder head 22 by means of a hose clamp 62. At its other end the invaginating tube 29 is reversely bent and the reversible bent end is fixed to the tubular piston rod 44 also by means of a hose clamp 62. To firmly grip the ends of the tube on the respective surfaces on which the ends of the invaginating tube 29 are attached these surfaces may be suitably roughened by knurling, scoring, or the like.

Disposed within the tubular piston rod bore adjacent the outer end thereof, is a charging check valve assembly 63. The charging check valve assembly 63, as shown in particular in FIGS. 8 and 9, includes a body 64 having a threaded portion 66 which is screwed into the internally threaded end of the piston rod bore 48 and a forwardly projecting reduced outer end portion 67. The threaded portion 66 is formed at its inner end with a groove 68 which receives a sealing gasket 69 such as an O-ring which is compressed against a shoulder 71 and thereby forms a substantially leak-proof seal.

Extending through the body 64 is a fluid charging passageway 72 including a closure cap chamber 73 into which there is threaded a closure cap 74 when the device has "been charged with hydraulic fluid. Communicating with the closure cap chamber 73 is a check valve chamber 75 which communicates at its other end with an orifice 76 opening into the tubular piston rod bore 48.

Threadably fastened within the check valve chamber 75 is a valve seat member 77 having an orifice 78 providing communication between the closure cap chamber 73 and the check valve chamber 75. Normally urged into seating over the inner end of the valve seat member orifice 78 by means of a biasing spring 79, is a ball check 80 which is unseated by the force of the hydraulic fluid during charging of the cushion device as more fully to be explained hereinafter.

Securing the bufler head 47 on the outer end of the tubular piston rod 44 is a fastening member 81 having an inner externally threaded portion 82 which is screwed into the internally threaded end of the tubular piston rod 44. Projecting outwardly from and integral with the threaded body portion 82 is reduced shank 83 which extends through an axial opening 84 formed in the buffer head. Threaded on the end of the shank 83 projecting into a recess formed on the outer face of the second cylinder 47 is a lock nut arrangement 85 which is tightened so that the end of the tubular piston rod 44 is firmly clamped to the second cylinder head 47. In order to facilitate the insertion of the buffer head fastening member 81 within the piston rodbore 48, the forward face of threaded end 82 may be provided with a pair of diametrically spaced openings 86 for receiving a spanning wrench, or the like.

The metering pin 14 may comprise a rod which may be of constant circular cross-sectional area along the 6 major portion of its length and is formed with a threaded end 88 which is threadably fastened within an axial blind opening 85 formed on the inner side of the first cylinder head 18. At the other end the metering pin may be formed with a projection 90 which is of substantially rectilinear section and in which projection there is formed a coaxially disposed threaded opening 91. The rectangular projection and the threaded opening therein are provided to facilitate the attachment of the metering pin within the unit as more fully described in my copending application U.S. Serial No. 318,384, filed October 23, 1963.

The circular cross section metering rod 87 extends through the piston head orifice 56 and is formed along the length thereof with flutes 92 of gradually tapering depth.

Upon relative movement between the cylinder 11 and the fluid displacement means 13, as occurs upon application of a force at either the cylinder head 18 or buffer head 47, the piston head 46 and metering pin 14 are positioned relatively to each other to that the flow through the orifice 56 as determined by the depth of flutes 92 at substantially any given distance of travel imparts a substantially constant force closure characteristic to the device 10.

To achieve this characteristic the flutes are designed to conform to the expression wherein A is the orifice area of any given position X, over the total nominal stroke or length of travel L of the device between its extended or contracted position (substantially corresponding to the length of the surface in which the flutes 92 are formed) and A is the initial orifice area defined by the orifice 56 and the flutes 92 at the beginning of the stroke under conditions where a completely rigid body is being cushioned from impact.

The provision of fastening the metering pin within a blind opening in the cylinder head 18 is particularly advantageous because it eliminates the possibility of hydraulic fluid leakage as would occur if the metering pin were fastened within an opening extending through the cylinder head 18.

The device 10 is charged With hydraulic fluid prior to the assembly of the cylinder head 47 and the insertion of fastening member 81 into the end of the piston rod 44. In this partially assembled state all of the remaining components are assembled with the exception that the closure cap or plug 74 is removed from the closure cap chamber 73 to provide an open passage.

Thereafter, a fitting on the end of a flexible hose or the like which is connected to the source of the hydraulic fluid is fastened to the reduced end 67 of the check valve assembly body 64. In this connection it should be mentioned that the reduced end 67 may be contoured or formed in any suitable manner to facilitate the connection of the particular fitting employed.

The hydraulic fluid being changed flows into the closure cap chamber 73, through the orifice 78, past the ball check 80 which is unseated by the force of the charged hydraulic fluid, and into piston rod bore 48 via the check valve chamber 75 and orifice 76. The hydraulic fluid introduced into the piston rod bore 48 flows into the low pressure chamber 93 of the cylinder 11 via the ports 49. At the same time the hydraulic fluid flows into the invaginating tube 29 via the annular opening 61 and through openings 94 formed in the piston rod 44 inwardly of the reversed end of the tube 29.

Fluid also flows through orifice 56 in the piston head and the flutes 92 into the high pressure chamber 95 of the device 10. The device 10 is charged to the extent that the pressure exerted by hydraulic fluid in the extended position thereof is maintained at a minimum, for example about 2 p.s.-i. Thereafter the plug 74 is inserted in the closure cap chamber 73.

To complete the assembly, the resilient return spring means 16 is positioned about the cylinder and the buffer head 47 is fastened to the end of the piston rod 44. As heretofore described, the buffer head is fastened to the piston rod 44 by means of the fastener 81 which is threaded into the threaded end of the piston rod bore 48 with the shank 83 on which the cylinder head 84 is fastened projecting outwardly. The resilient spring means 16 is generally formed from a plurality of helical springs 16a, 16b, 16c arranged to operate in tandem as shown. To fasten the cylinder head on the stud, it may be necessary to employ a fixture or the like for holding the springs 16a, 16b, 16c sufliciently compressed below the end of the piston rod 44 so that the buffer head 47 may be fastened without interference from the springs. When the springs 16a, 16b, 160 are compressed, the buffer head 47 is positioned on the shank 83 and the lock nut arrangement 85 is tightened to securely fasten the head 47 on to the end of the piston rod 44. Thereafter, the spring fixture (not shown) may be removed so that the return springs 16a, 16b and 160 are operative to maintain the cylinder 11 and fluid displacement means 13 in the normal extended position shown in FIG. 1.

Assuming that the hydraulic cushion device is employed in a railway car for the purpose for which it is primarily intended and is disposed between and operatively associated with the coupler carrying structure and the lading supporting structure for cushioning the force of impact applied on the couplers, the device 10 is normally in the fully extended position as shown in FIG. 1. Upon the application of a shock impact in either buff or draft at the couplers, the device which is associated with the coupler carrying structure and the lading supporting structure such that the cylinder 11 and piston head 46 start movement toward each other.

As the cushion device 10 thus contracts under the force being cushioned, the metering pin 14 displaces hydraulic fluid contained within the bore 48 of the piston rod 44 outwardly through the ports 49 into the low pressure chamber 93 from where it flows via the annular opening 61 into the invaginating tube 29. At the same time the piston head 46 displaces fluid in the high pressure chamber 95 through the orifice .56 into the piston rod bore 48. The hydraulic flow through the orifice 56 is determined by its position relative to the flutes 92 which, as heretofore described, are formed so as to impart a substantially constant resisting force closure characteristic to the hydraulic cushion device 10. In other word, the flutes 92 of the metering pin 14 are cooperative with the orifice 56 so that the flow of hydraulic fluid therethrough for substantially each increment of travel of the piston head 46 relative to the cylinder 11 results in a substantially constant cushioning effect resisting the force of impact.

The hydraulic flow caused by the relative movement of the piston head 46 and the cylinder 11 as above described flows from the high pressure chamber 95 through the orifice 56 and into the bore 48 of the tubular piston rod 44. Hence, the hydraulic fluid flows radially outward through the ports 49 into the low pressure chamber 93 of the cylinder bore 12. The hydraulic flow through the ports 49 occurs at a relatively high velocity so that a turbulence is created as the displaced fluid enters the low pressure chamber 93. The turbulence is caused at least in part by the radially directed flow of the hydraulic fluid impinging directly against the inner wall of the cylinder 11 so that a major portion of the kinetic energy of the hydraulic fluid is dissipated in the form of heat. In this connection, it is to be noted that the stop ring 96 contacting the intermediate cylinder head 22 is effective to limit the volume of the low pressure chamber 93 in the fully contracted position of the device 10 and in this manner provides a chamber into which the hydraulic fluid displaced by the piston may freely enter as described above and thereby dissipate the kinetic enengy in the form of heat under minimum shock or load conditions.

During contraction of the cushioning device 10 the high pressure chamber 95 continues to reduce in volume because of the advancement of the piston head 46 toward the cylinder head 18. The hydraulic fluid passing through the orifice fills the low pressure chamber 93, while at the same time a volume of hydraulic fluid equivalent to that displaced by the total entry into the chamber 93 of the cylinder 11 passes through the annular opening 61 and into the reservoir defined by the invaginating tube 28 which inflates or expands and assumes substantially the position shown in FIG. 2.

After the shock has been fully dissipated the compression springs 16a, 16b and 16c acting in tandem between the cylinder heads 18 and 47 are operative to return the hydraulic cushion components to the inital position. During this movement, under the action of the compression springs 16a, 16b and 160, the hydraulic fluid flow previously described is reversed and the invaginating tube deflates and returns to the position shown in FIG. 1, thereby assuring that the hydraulic fluid displaced by the piston is restored to its normal operative position.

What is claimed is:

1. In a hydraulic cushion device including a cylinder having a bore, a first cylinder head fixed to one end of said cylinder, an intermediate cylinder head fixed within said cylinder bore inwardly of the open end of said cylinder, said intermediate cylinder head defining on one side thereof with said first cylinder head a hydraulic fluidfilled bore and on the opposite side thereof adjacent said open end a flexible boot reservoir chamber, an axial opening in said intermediate cylinder head, a piston head reciprocable within said hydraulic fluid-filled bore and having a hydraulic fluid orifice means formed therein, a tubular piston rod fixed on one end to said piston head for receiving within the bore thereof the hydraulic fluid passing through said orifice means, said tubular piston rod extending outwardly through said axial opening in said intcrmediate cylinder head, a flexible boot reservoir connected between said intermediate cylinder head and said end of said tubular piston rod extending outwardly of said intermediate cylinder head whereby said flexible boot reservoir is expandable within said flexible boot reservoir chamber, hydraulic fluid passage means providing communication between said hydraulic fluid-filled bore and said flexible boot chamber, a buffer head fixed to the other end of said tubular piston rod, and return spring means disposed between said first cylinder head and said bufler head; the improvement comprising means for fixing said intermediate cylinder head Within said cylinder bore in fluid-tight and sealing relationship, said means including first shoulder means formed on the periphery of said intermediate cylinder head, a compressible sealing gasket disposed about said periphery adjacent a second shoulder means longitudinally spaced from said first shoulder means, a compression ring slidably disposed about said periphery between said first shoulder means and said sealing gasket, and a plurality of angularly spaced clip means disposed between said first shoulder means and said compression ring, said clip means being initially transversely bent and having one end thereof abutting said first shoulder means and said other end abutting said compression ring so that upon straightening thereof the effective length of said clip means is increased whereby the compression ring is urged toward said sealing gasket to compress the latter against said second shoulder means.

2. The improvement as defined in claim 1 wherein said clip means are each bent to a substantially V configuratron, said V-clips being angularly spaced about said periphery of said intermediate cylinder head in an inverted attitude so that upon straightening thereof said clips are operative to slidably urge said compression ring toward said second abutment means and thereby to compress said sealing gasket therebetween.

3. The improvement as defined in claim 2 wherein said cylinder is provided with openings angularly spaced complementary to said clip means for providing access thereto to straighten said clip means.

4. In a hydraulic cushion device including a cylinder having a bore, a first cylinder head fixed to one end of said cylinder, an intermediate cylinder head fixed within said cylinder bore inwardly of the open end of said cylinder, said intermediate cylinder head defining on one side thereof with said first cylinder head a hydraulic fluid-filled bore and on the opposite side thereof adjacent said open end a flexible boot reservoir chamber, an axial opening in said intermediate cylinder head, a piston head reciprocable within said hydraulic fluid-filled bore and having a hydraulic fluid orifice means formed therein, a tubular piston rod fixed on one end to said piston head for receiving within the bore thereof the hydraulic fluid passing through said orifice means, said tubular piston rod extending outwardly through said axial opening in said intermediate cylinder head, a flexible boot reservoir connected between said intermediate cylinder head and said end of said tubular piston rod extending outwardly of said intermediate cylinder head whereby said flexible boot reservoir is expandable within said flexible boot reservoir chamber, hydraulic fluid passage means providing communication between said hydraulic fluid-filled bore and said flexible boot chamber, a bufier head fixed to the other end of said tubular piston rod, and return spring means disposed between said first cylinder head and said buffer head; the improvement comprising means for fixing said intermediate cylinder head within said cylinder bore in fluid-tight and sealing relationship, said means including first shoulder means formed on the periphery of said intermediate cylinder head, a compressible sealing gasket disposed about said periphery adjacent second shoulder means longitudinally spaced from said first shoulder means, a compression ring slidably disposed about said periphery between said first shoulder means and said sealing gasket, and a plurality of angularly spaced intermediate cylinder head fastening means threaded into said cylinder, said fastening means including camming-like surfaces engageable with opposing sides of said first shoulder means and said compression ring so that upon threading thereof to fix said intermediate cylinder head within said bore said compression ring is slidably urged toward said second shoulder means and thereby to compress said sealing gasket therebetween.

5. The improvement as defined in claim 4 wherein said camming-like surfaces include a threaded shank of substantially constant circular cross-section :along its length which terminates in a substantially conical tip.

6. The improvement as defined in claim 4 wherein said camming-like surfaces include a threaded shank of substantially constant circular cross-section along its length which terminates in a substantially conical tip, and wherein the opposing side of said compression ring is formed 10 within an inclined surface complementary to said conical tip for at least :a portion of the height of said opposing side.

7. A hydraulic cushion comprising a cylinder having a bore, a first cylinder head fixed to one end of said cylinder, an intermediate cylinder head fixed within said cylinder bore inwardly of the open end of said cylinder, said intermediate cylinder head defining on one side thereof with said first cylinder head :a hydraulic fluid-filled bore and on the opposite side thereof adjacent said open end a flexible boot reservoir chamber, an axial opening in said intermediate cylinder head, a piston head reciprocable within said hydraulic fluid-filled bore and having a hydraulic fluid orifice means formed therein, a tubular piston rod fixed at one end to said piston head for receiving hydraulic fluid flowing through said orifice means, said tubular piston rod extending outwardly through said axial opening in said intermediate cylinder head, a flexible boot reservoir connected between said intermediate cylinder head and the length of said tubular piston rod extending outwardly through said .axial opening whereby said flexible boot reservoir is expandable within said flexible boot reservoir chamber, a charging check valve assembly disposed within the bore of said tubular piston rod inwardly of the outwardly extending end thereof, said check valve assembly including a body portion threadably fastened within said tubular piston rod bore, a resilient sealing gasket disposed about the inner end of said body portion and which is compressed against shoulder means provided within said bore thereby to form a fluid-tight seal, buifer head fastening means closing off said outwardly extending end of said tubular piston rod, said fastening means including an outwardly extending post, a buffer head means fixing said buffer head on said post, and return spring means disposed between said first cylinder head and said buifer head.

8. The invention as defined in claim 7 wherein said bufifer head fastening means includes an end portion threadably fastened within said bore, and said post is integral with said end portion and of lesser diameter, and wherein said outer face of said end portion is provided with diametrically spaced openings for receiving a tool employed to thread said fastening means within said tubular piston rod bore.

References Cited by the Examiner UNITED STATES PATENTS 2,395,595 2/1946 Underwood 267-64 2,527,980 10/1950 Bachman 267-64 3,035,714 5/1962 Peterson 267-34 X 3,035,827 5/1962 Peterson 267-34 3,148,869 9/1964 Peterson 267-1 ARTHUR L. LA POINT, Primary Examiner. W. B. WILBER, Assistant Examiner. 

1. IN A HYDRAULIC CUSHION DEVICE INCLUDING A CYLINDER HAVING A BORE, A FIRST CYLINDER HEAD FIXED TO ONE END OF SAID CYLINDER, AN INTERMEDIATE CYLINDER HEAD FIXED WITHIN SAID CYLINDER BORE INWARDLY OF THE OPEN END OF SAID CYLINDER, SAID INTERMEDIATE CYLINDER HEAD DEFINING ON ONE SIDE THEREOF WITH SAID FIRST CYLINDER HEAD A HYDRAULIC FLUIDFILLED BORE AND ON THE OPPOSITE SIDE THEREOF ADJACENT SAID OPEN END A FLEXIBLE BOOT RESERVOIR CHAMBER, AN AXIAL OPENING IN SAID INTERMEDIATE CYLINDER HEAD, A PISTON HEAD RECIPROCABLE WITHIN SAID HYDRAULIC FLUID-FILLED BORE AND HAVING A HYDRAULIC FLUID ORIFICE MEANS FORMED THEREIN, A TUBULAR PISTON ROD FIXED ON ONE END TO SAID PISTON HEAD FOR RECEIVING WITHIN THE BORE THEREOF THE HYDRAULIC FLUID PASSING THROUGH SAID ORIFICE MEANS, SAID TUBULAR PISTON ROD EXTENDING OUTWARDLY THROUGH SAID AXIAL OPENING IN SAID INTERMEDIATE CYLINDER HEAD, A FLEXIBLE BOOT RESERVOIR CONNECTED BETWEEN SAID INTERMEDIATE CYLINDER HEAD AND SAID END OF SAID TUBULAR PISTON ROD EXTENDING OUTWARDLY OF SAID INTERMEDIATE CYLINDER HEAD WHEREBY SAID FLEXIBLE BOOT RESERVOIR IS EXPANDABLE WITHIN SAID FLEXIBLE BOOT RESERVOIR CHAMBER, HYDRAULIC FLUID PASSAGE MEANS PROVIDING COMMUNICATION BETWEEN SAID HYDRAULIC FLUID-FILLED BORE AND SAID FLEXIBLE BOOT CHAMBER, A BUFFER HEAD FIXED TO THE OTHER END OF SAID TUBULAR PISTON ROD, AND RETURN SPRING MEANS DISPOSED BETWEEN SAID FIRST CYLINDER HEAD AND SAID BUFFER HEAD; THE IMPROVEMENT COMPRISING MEANS FOR FIXING SAID INTERMEDIATE CYLINDER HEAD WITHIN SAID CYLINDER BORE IN FLUID-TIGHT AND SEALING RELATIONSHIP, SAID MEANS INCLUDING FIRST SHOULDER MEANS FORMED ON THE PERIPHERY OF SAID INTERMEDIATE CYLINDER HEAD, A COMPRESSIBLE SEALING GASKET DISPOSED ABOUT SAID PERIPHERY ADJACENT A SECOND SHOULDER MEANS LONGITUDINALLY SPACED FROM SAID FIRST SHOULDER MEANS, A COMPRESSION RING SLIDABLY DISPOSED ABOUT SAID PERIPHERY BETWEEN SAID FIRST SHOULDER MEANS AND SAID SEALING GASKET, AND A PLURALITY OF ANGULARLY SPACED CLIP MEANS DISPOSED BETWEEN SAID FIRST SHOULDER MEANS AND SAID COMPRESSION RING, SAID CLIP MEANS BEING INITIALLY TRANSVERSELY BENT AND HAVING ONE END THEREOF ABUTTING SAID FIRST SHOULDER MEANS AND SAID OTHER END ABUTTING SAID COMPRESSION RING SO THAT UPON STRAIGHTENING THEREOF THE EFFECTIVE LENGTH OF SAID CLIP MEANS IS INCREASED WHEREBY THE COMPRESSION RING IS URGED TOWARD SAID SEALING GASKET TO COMPRESS THE LATTER AGAINST SAID SECOND SHOULDER MEANS. 